
import java.util.ArrayList;
import java.util.List;

public class Test {

	public static void main(String[] args) {

        Integer num = null;
        int a = num;
        System.out.println(a);
	}
    
    private static void substring(){
        
        String temp = "abcda";
        String tmp = temp.substring(4);
        System.out.println(tmp);
    }
    
    
    private static void isString(){
        
        String temp = "abcda";
        List<String> list = new ArrayList<String>();
        
        if(temp instanceof String){
            System.out.println("this is string");
        }else{
            System.out.println("this is not string");
        }
    }
}